how antenna works
The definition below is from the Antenna Handbook MCRP 6-22D pg. 38.
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“When an alternating electric current flows through a conductor (wire), electric and magnetic fields are created around the conductor.
If the length of the conductor is very short compared to a wavelength, the electric and magnetic fields will generally die out within a distance of one or two wavelengths. However, as the conductor is lengthened, the intensity of the fields enlarge. Thus, an ever increasing amount of energy escapes into space. When the length of the wire approaches one-half of a wavelength at the frequency of the applied alternating current, most of the energy will escape in the form of electromagnetic radiation. For effective communications to occur, the following must exist: alternating electric energy in the form of a transmitter, a conductor or a wire, an electric current flowing through the wire, and the generation of both electric and magnetic fields in the space surrounding the wire.”